1. Field of the Invention
The present invention relates to workholding apparatuses and, more particularly, is directed to removable jaws for vise-like workholders.
2. Description of the Invention Background
During the machining of a "workpiece" on a machine tool apparatus such as a milling machine or the like, single or multiple workpieces are typically held in place by a precision vise or clamping member ("a vise-like workholder") that is attached to the machine. Exemplary vise-like workholders that are adapted to hold a single workpiece are disclosed in U.S. Pat. No. 4,928,937 to Bernstein, U.S. Pat. No. 4,898,371 to Mills et al., U.S. Pat. No. 4,569,509 to Good, and U.S. Pat. No. 4,098,500 to Lenz.
As can be gleaned from review of those patents, such vise-like workholders are adapted to clamp a workpiece between opposing jaw members operably supported on a base. Typically, one jaw member is fixed and the other jaw member is movable relative to the fixed jaw member by means of a screw member housed within the base. As the movable jaw member is moved toward the fixed jaw member, the workpiece is clamped therebetween.
Another vise-like workholder is disclosed in U.S. Pat. No. 2,564,138 to Walker. This workholder includes jaw support members that each have a camming portion that is adapted to engage a corresponding undercut portion provided on a jaw member. The rear portion of each jaw member is also provided with a transverse slot that is adapted to receive a transverse bar formed in a corresponding jaw support member. A second transverse slot is provided in the front portion of each jaw member for receiving a corresponding spring strip that is attached to the forward portion of the jaw member. The spring strip serves to bias the jaw member in a slightly upward direction relative to the jaw support member. This jaw member arrangement, however, is less desirable because debris can accumulate in the exposed slot and become lodged between the jaw support member and the jaw member as the support member is advanced on the vise base.
Other vise-like workholders are capable of holding two or more workpieces in side-by-side orientations. Examples of such "two-station" workholders are disclosed in U.S. Pat. No. 5,098,073 to Lenz, U.S. Pat. No. 5,094,436 to Stephan, III, U.S. Pat. No. 5,022,636 to Swann, U.S. Pat. No. 4,934,674 to Bernstein, and U.S. Pat. No. 4,529,183 to Krason et al. Such workholders typically comprise a base that has a central jaw member fixed thereto. Two outer jaw members are operably supported on the base and can be selectively positioned relative to the fixed central jaw member by a vise screw that is operably received in a longitudinal cavity provided in the base.
The workpiece or workpieces are typically supported on the workholder bases of each of the above-mentioned workholders and are secured in position by at least two jaw members. Prior jaw member arrangements typically employed hardened steel jaw plates that were removably attached to a jaw member that was movably supported on the base. Steps were often machined in the jaw plates to accommodate workpieces of different heights. However, the number of different workpiece configurations that could be clamped utilizing such system were generally limited to shapes with at least one straight side.
One type of workholder equipped with a removable jaw member is disclosed in U.S. Pat. No. 463,332 to Giles. The removable jaw member employed by this workholding device has a socket formed therein with undercut portions adapted to receive a support member having beveled edges. To attach the jaw member to the support member, the beveled portion of the support member is aligned with the jaw member socket such that it can be inserted therein. Thereafter, the jaw member is rotated ninety degrees causing the beveled edges of the support member to engage the corresponding undercut portions of the jaw member socket. Because the socket occupies a large portion of the jaw member, this removable jaw member is ill-suited to have workpiece retaining grooves or cavities machined in its upper surface due to the relatively small amount of material provided between the top of the jaw member and the support member socket.
Another workholding device that employs a removable jaw member is disclosed in U.S. Pat. No. 2,880,638 to Muggli et al. This removable jaw member arrangement includes a jaw "nut" or support member that is adapted to support the removable jaw member on a vise base. The removable jaw member has a cavity formed therein that is adapted to receive a portion of the jaw nut that protrudes above the work surface of the vise base. The cavity and the jaw nut have corresponding sloping surfaces that are designed to receive a hardened semi-spherical insert positioned therebetween. The insert is retained in that position by an adjusting screw that extends through the rear portion of the jaw member to engage a flat surface on the rear of the jaw nut. This arrangement requires the use of hand tools to change the removable jaw member and the retaining screw is susceptible to being loosened during the machining process. In addition, there is not sufficient material between the upper surface of the jaw member and the cavity to accommodate grooves or retaining cavities in the top of the removable jaw member.
U.S. Pat. No. 4,928,937 to Bernstein also discloses a machine vise that has a fixed jaw member and a movable jaw member. The movable jaw member is removably attached to a movable support member in the manner taught in U.S. Pat. No. 2,880,638 to Muggli et al. However, the Bernstein patent teaches that the set screw can be replaced with a spring-biased detent that is designed to engage a cam surface on the movable support member to retain the jaw member on the support member. The detent also serves to urge the jaw member into sliding contact with the base. However, due to the relatively small amount of material between the upper surface of the jaw member and the cavity therein, such jaw member attachment arrangement is ill-suited for use in applications wherein it is desirable to machine workpiece retaining grooves or cavities in the upper surface of the jaw member. In addition, each jaw member must be fitted with a spring-loaded detent.
Another detachable jaw member arrangement for a vise-like workholding apparatus is disclosed in U.S. Pat. No. 5,024,427 to Swann. This device utilizes a removable pin arrangement for attaching a removable jaw member to a jaw nut. Such pin arrangement, however, requires the jaw nut to have a relatively high portion protruding into the jaw member rendering that portion of the jaw member unavailable to have workpiece retaining grooves, etc. machined therein.
Yet another workholding device with detachable jaw members is disclosed in U.S. Pat. No. 5,458,321 to Durfee, Jr. The device disclosed in this patent includes a movable jaw support member that is operably supported within a groove in a vise base. A portion of the support member protrudes from the groove in the base and has a transverse groove in one end thereof and a spring biased retaining pin which protrudes from the opposite end thereof along an axis that is perpendicular to the transverse groove. A cavity is provided in the removable jaw member that is sized to receive the movable jaw support member therein. Two transverse pins are provided in the jaw member and are each arranged to engage the transverse groove in the movable support member depending upon the orientation by which the jaw member is positioned on the support member. A shallow groove or undercut is also provided in the jaw member directly below each transverse pin. To attach the jaw member to the support member, the jaw member is placed over the support member such that one of the transverse pins engages the transverse groove therein. Thereafter, the jaw member is pivotally pressed onto the support member such that the spring biased retaining pin engages a corresponding undercut portion located in the jaw member. Thus, the jaw member is removably secured to the movable member by virtue of the engagement between one of the transverse pins and the transverse groove in the support member and the retaining pin's engagement with one of the undercut portions in the jaw member. This jaw member arrangement, however, is expensive to fabricate because each jaw member must be equipped with transverse pins. In addition, the transverse pins limit the amount of jaw member material that can be removed from the upper surface of the jaw member to accommodate various workpieces. Furthermore, the jaw cannot be installed or removed by vertical movement and, indeed, the user must utilize a prybar-like tool to remove the jaw from the support member. Thus, if such a tool is misplaced or lost, valuable machining time may be lost during changeover operations.
Accordingly, there is a need for a removable jaw member for a vise-like workholder that is economical to fabricate.
There is a further need for a removable jaw member having the above-mentioned attributes that can also accommodate cavities and grooves machined in its upper surface and clamping surfaces to enable the jaw member to clamp workpieces having irregular shapes.
There is yet another need for a detachable jaw for a vise-like apparatus that can be attached and removed from the apparatus without the use of additional tools.
There is still another need for a detachable jaw for a vise-like workholding apparatus that lends itself to automated attachment and detachment to the apparatus without the use of additional tools.
Another need exists for a vise-like workholding apparatus that includes removable jaws that can have grooves and cavities machined in their upper surface and that can be easily attached and detached from the apparatus.